Anesthetic composition and method of anesthetizing the eye

ABSTRACT

A topical ophthalmic anesthetic composition includes a formulation with an amount of articaine to provide anesthetic properties when applied topically to the eye, and a pH, viscosity, osmolality, dissociation constant, and additives such as antioxidants, buffers, methylcellulose, to achieve efficacy and safety. The composition can contain articaine in amounts of about 4.0% w/v to about 12.0% w/v and have a pH of about pH 3.5 to pH 7.0. The buffer can be borate/mannitol complex obtained from boric acid or salt thereof and D-mannitol. The articaine formulations can achieve adequate anesthesia of the internal aspect of the eye wall by topical application, without the use of an injectable anesthetic. Exemplary implementations of the disclosure include formulations include articaine in an amount of at least 7.0% w/v, where the formulation is an aqueous solution, a gel, an ointment, or in an encapsulated form.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 16/811,798, filed on Mar. 6, 2020, which claimspriority to U.S. Provisional Patent Application No. 62/824,207, filedMar. 26, 2019, which is hereby incorporated by reference in itsentirety. The application further claims priority to PCT/US2019/024239,filed on Mar. 27, 2019, which claims priority to U.S. Provisional PatentApplication No. 62/648,660, filed Mar. 27, 2018, and priority to U.S.Provisional Patent Application No. 62/824,207, filed Mar. 26, 2019, theentire contents of which are incorporated herein by reference.

BACKGROUND 1. Field of Disclosure

Generally, exemplary embodiments of the present disclosure relate to ananesthetic composition and a method of administering the anestheticcomposition to a patient, and particularly for anesthetizing at least aportion of the eye. The disclosure relates to a topical anestheticcomposition or formulation that can be applied topically to the surfaceof the eye. Exemplary implementations of certain embodiments of thedisclosure provide methods for topically applying a topical anestheticformulation, for example a drop, to achieve a high level of pars planaanesthesia, sufficient to permit intravitreal injection without unduediscomfort to the patient. Exemplary implementations of certainembodiments of the present disclosure provide methods for applying atopical solution comprising articaine to achieve anesthesia of thesurface of the eye as well as the internal aspect of eye wall.

2. Background of Disclosure

Injections of pharmacologic agents into the vitreous cavity for thepurpose of treating various disorders of the retina as well asintraocular inflammatory disease have become the mainstream. In 2016,CMS alone reimbursed for approximately 2.75 million injections. Inalmost all cases, these injections are typically made through the parsplana. An injection into the eye through the pars plana with the needleoriented properly, will be posterior to the human lens or intraocularlens implant, but anterior to the retina thereby avoiding damage to thelens and retina. The pars plana is a ring zone that surrounds theperimeter of the eye extending from 3.0 to 5.5 mm from the edge of thecornea. The prior topical agents, such as proparacaine, can achieveanesthesia on the external surface of the eye, but do not numb oranesthetize the internal aspect of the pars plana, which is extremelysensitive.

There are no known approved topical anesthetics that produce anesthesiaof the internal aspect of the pars plana. Currently, physiciansinitially inject lidocaine under the conjunctiva (covering tissue of theeye) and then execute a second injection through the pars plana. In someapplications lidocaine gel is used prior to performing the intravitrealinjection. Patients often report moderate to severe discomfort with eachof these approaches.

Some complications of intravitreal injection can occur, includingendophthalmitis where an infection develops inside the eye. Treatment ofendophthalmitis is often successful but permanent visual loss to atleast to some degree is common. Therapy involves further intravitrealinjections of antibiotics and/or steroids, and vitrectomy surgery.Blindness or loss of the eye is not uncommon. Ophthalmologists seek toprevent complications caused by infections although many of theanesthetics used are not always sterile.

Conventionally articaine has only been employed through an injectableroute. Currently available topical ophthalmic anesthetics perform on theexternal ocular surface but do not penetrate well enough to producesufficient anesthesia of the internal aspect of the eye wall. Thisregion is exquisitely sensitive to penetration, pressure, and laser orfreezing applications. One commonly performed ophthalmic procedure isinjection of various pharmacologic agents into the eye. To achieveuniformly adequate anesthesia for this injection, the physician firstperforms a periocular injection of an anesthetic agent, wait for theanesthetic to become effective, and then perform the intraocularinjection.

Articaine formulations containing not more than 4% articaine and avasoconstrictor, which is commonly epinephrine, are known for use as aninjectable anesthetic that is formulated for injection into the tissuein the patient. Such formulations are commonly used in dentistry toperform dental procedures. The prior compositions are generally notsuitable or effective for topical administration or applications in theeye.

There currently no standard procedures for ocular anesthesia and thepreparations for intravitreal injections. Furthermore, there are noapproved drugs specifically for treating the eye prior to intravitrealinjections. The pars plana is a unique region of the eye. Standardtopical ophthalmic agents achieve anesthesia of the external surface ofthe eye. However, as the injection needle penetrates the interior aspectof the pars plana into the vitreous cavity, patients without anesthesiaexperience severe pain to the extent that completion of the injection isnot possible.

While the prior compositions and formulations generally have beensuitable for the intended purposes, there is a continuing need forimproved anesthetic compositions.

SUMMARY

Exemplary embodiments of the present disclosure provide an anestheticcomposition containing articaine. The anesthetic composition is suitablefor topical ophthalmic use by topical application to the surface of theeye to achieve a level of anesthesia sufficient for intravitrealinjections and other medical procedures. The anesthetic composition canbe administered in an amount sufficient to permit intravitreal injectionin the eye without undue discomfort to the patient.

The topical ophthalmic composition includes articaine in a sufficientlyhigh concentration to induce anesthesia to the eye by topicaladministration prior to performing various medical procedures, includingsurgical procedures. The composition is particularly suitable forproviding anesthesia to the eye to enable an injection in or through thepars plana of the eye with minimal or no pain to the patient.

Exemplary embodiments of the present disclosure include formulations,and/or modification and/or use thereof, comprising articaine, which canbe an intermediate potency, short acting amide local anesthetic. Themetabolism of articaine can be rapid due to the presence of an estergroup in molecular structure. Articaine has been previously administeredby injection for peripheral nerve, spinal, epidural, periocular, orregional nerve block.

In one embodiment, a topical ophthalmic anesthetic composition includesarticaine in an amount effective to provide an anesthetic effect to theeye of the patient without the need for repeated application orinjection of an anesthetic into the eye. Articaine can be included inthe topical anesthetic composition in amounts and concentrations toprovide the desired anesthetic properties by a controlled dosage. Thecomposition can include articaine in amounts of up to about 13% w/vbased on the total volume of the composition. In some embodiments, thecomposition can include articaine in amounts of about 4% w/v to about12% w/v based on the total volume of the composition. The higherconcentration of articaine in the ophthalmic composition can beadministered at smaller dosages while providing the desired anestheticeffects to the eye.

In one embodiment, the topical ophthalmic anesthetic composition is anaqueous composition that contains about 7.0% w/v to about 8.5% w/varticaine and a buffer that is not reactive with articaine or/and doesnot promote decomposition of articaine. The buffer in an embodiment canprovide a pH of about pH 3.5 to about pH 7.0 and an osmolality of about280 to about 320 mOsm/kg. In an embodiment, the ophthalmic anestheticcomposition has pH of about pH 4.5 to about pH 5.0. The buffer in oneembodiment is a complex obtained from an acid and a sugar alcohol. Theacid can be selected from the group consisting of boric acid, citricacid, and mixtures thereof. In one particular embodiment, the acid isboric acid. The sugar alcohol can be D-mannitol, sorbitol, and mixturesthereof. A particularly suitable buffer is a borate/mannitol complexobtained from boric acid or a borate salt and D-mannitol. The buffer canbe a complex obtained from about 13 wt % to about 17 wt % boric acid andabout 83 wt % to about 88 wt % D-mannitol, based on the total weight ofthe boric acid and D-mannitol. The anesthetic composition in theembodiment can include sodium acetate trihydrate, acetic acid, anddisodium edetate dihydrate. The anesthetic composition can have a pHrange of about pH 4.5 to about pH 7.0.

The topical ophthalmic anesthetic composition in one embodiment is anaqueous mixture of at least about 7.5% w/v articaine, a buffer includinga complex formed from boric acid and D-mannitol, sodium acetate, aceticacid, disodium edetate, and the balance water where the composition hasa pH of pH 4.5 to about pH 5.0. A pH of less than about pH 5.0 has beenfound to improve long term stability of the articaine composition.

In another embodiment, the topical ophthalmic anesthetic composition isa stable aqueous composition containing articaine in an amount of atleast about 8% w/v, at a pH of about pH 4.5 to about pH 5.5, a bufferand excipients that are not reactive with articaine and do not promotedecomposition of the articaine in the aqueous composition. Thecomposition can include articaine as the only anesthetic agent orcompound and is typically in the absence of a vasoconstrictor, such asepinephrine. In one embodiment, the composition is in the absence ofsodium metabisulfite and/or sodium bisulfate. The buffer in thisembodiment is a borate/mannitol complex.

The features of the aqueous topical ophthalmic anesthetic compositioncomprise about 4.0% w/v to about 12.0% w/v articaine, and a buffer in anamount to provide a pH of about pH 3.5 to about pH 7.0, where the bufferis non-reactive with and stabilizes the articaine. The buffer can be acomplex obtained from boric acid and D-mannitol.

In an embodiment, the aqueous ophthalmic anesthetic compositioncomprises about 4% w/v articaine, a buffer comprising NaOH and HCl, a pHof about pH 5.5, a pKa of about 7.8, a viscosity of about 20-25 cp, anosmolality of about 275 to 1171 mOsm/kg, and a tonicity of about 0.5 to5.0%.

In another embodiment, the aqueous topical anesthetic compositioncomprises 80 mg/g articaine HCl, 1.373 mg/g sodium phosphate monobasicmonohydrate, 1.413 mg/g sodium phosphate dibasic anhydrous, 8.1 mg/ghydroxypropylmethyl cellulose, 4 mg/g PEG400, and where said compositionhas a pH of pH 6.0 to pH 7.0, a viscosity of 743-803 cp, and anosmolality of 517 mOsm/kg.

Another feature of this disclosure provides a method for inhibiting painand/or discomfort to the eye of a patient during various surgicalprocedures in the eye and/or an injection in the eye by a needle. Themethod introduces a topical anesthetic composition to the eye in anamount to induce anesthesia to the eye where the anesthetic compositioncontains an effective amount of articaine to treat the surface of theeye and the tissue below the surface including the pars plana. Themethod is particularly suitable for procedures for injecting a substanceor medication into the eye where the surface of the eye is treated withthe topical composition containing at least 4.0% w/v articaine and anon-reactive buffer to provide a pH about pH 4.5 to about pH 7.0 andgenerally about pH 4.5 to about pH 5.5. In other embodiments, thetopical composition has a pH 4.5 to about pH 5.0.

These and other features will become apparent from the followingdetailed description.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The matters exemplified in this description are provided to assist in acomprehensive understanding of exemplary embodiments of the disclosure.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of thedisclosure. Also, descriptions of well-known functions and constructionsare omitted for clarity and conciseness. In the disclosure, the rangesof the various components and features of the composition can becombined with ranges or features of other embodiments. The embodimentsdescribed are not intended to be limiting such that features of oneembodiment can be combined with other embodiments.

The phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein isto encompass the items listed thereafter and equivalents thereof as wellas additional items. The embodiments are not intended to be mutuallyexclusive so that the features of one embodiment can be combined withother embodiments as long as they do not contradict each other. Terms ofdegree, such as “substantially”, “about” and “approximately” areunderstood by those skilled in the art to refer to reasonable rangesaround and including the given value and ranges outside the given value,for example, general tolerances associated with manufacturing, assembly,and use of the embodiments. The term “substantially” when referring to astructure or characteristic includes the characteristic that is mostlyor entirely present in the characteristic or structure.

Exemplary embodiments of the present disclosure provide methodologiesemploying a topical anesthetic composition or formulation containingarticaine with improved anesthetizing effect of the eye and with reducedrisk of infection in the eye. As used herein the term composition andformula are used interchangeably to refer to the mixture or combinationof compounds, including active compounds and excipients. In theembodiments described, the composition is a aqueous mixture containingarticaine, buffers and other excipients to obtain a stable compositionwith a suitable pH, osmolality and articaine concentration for topicalapplication to the eye.

The topical ophthalmic anesthetic composition is an anestheticcomposition containing an effective amount of the anesthetic agent toanesthetize the surface and internal aspects of the eye of a patient bytopical administration for performing various medical procedures, suchas an intravitreal injection. In one embodiment, the topical ophthalmicanesthetic composition is prepared as a topical composition and applieddirectly to the surface of the eye to anesthetize the surface of the eyeand the internal aspect of the eye. The topical ophthalmic anestheticcomposition contains articaine in an amount effective to provide theanesthetic effect to the eye to reduce or inhibit pain and/or discomfortto the patient during a medical procedure in the eye, such as anintravitreal injection or other surgical procedure.

The topical ophthalmic anesthetic composition containing articaine canhave various ranges of pH and various amounts of articaine depending onthe buffer and stabilizing agents included in the anestheticcomposition. In the embodiments of the anesthetic composition, thebuffers and stabilizing agents provide an effective topical anestheticcomposition where the buffers and stabilizing agents enable differentranges of pH to stabilize the composition and maintain a suitableosmolality for the composition.

The topical ophthalmic anesthetic composition in various embodimentscontain about 4.0% w/v to about 13% w/v articaine at a pH to stabilizethe articaine and at a pH to minimize discomfort to the patient.Suitable anesthetic compositions can also be prepared containing atleast 6% w/v articaine. The composition in the embodiments described isan aqueous ophthalmic anesthetic composition. In one embodiment, thetopical ophthalmic anesthetic composition contains articaine in anamount of at least about 7.0% w/v and generally at least about 8.0% w/varticaine based on the total volume of the composition. In anotherembodiment, the topical ophthalmic anesthetic composition containsarticaine in an amount of at least about 8.5% w/v articaine. As usedherein, w/v refers to grams per 100 ml of the composition. Theophthalmic composition generally includes at least about 4% w/varticaine and up to about 8.5% w/v articaine. In one embodiment, thetopical composition includes at least about 7.0% and generally at leastabout 8.0% w/v articaine. The articaine as used in the topicalcompositions is typically prepared from the hydrochloride salt.

The topical ophthalmic composition in an embodiment includes articainein an amount of at least about 4% w/v and a buffer to control the pH inthe desired range. In one embodiment, the topical composition has a pHin the range of pH 4.5 to pH 7.0. Other embodiments, can have a pH ofabout pH 6.0 to about pH 7.0. In still other embodiments, the topicalcomposition can have a pH less than pH 5.0. The buffer is non-reactivewith the articaine at pH 4.0 to pH 7.0 to inhibit degradation of thearticaine and provide a storage stable composition. The topicalophthalmic composition can include articaine in an amount greater thanabout 4.0% w/v and a buffer to provide a stable mixture at a pH of aboutpH 6.0 or below where the buffer is not reactive with the articaine.

The pH of the topical ophthalmic composition is generally adjusted tomaintain a desired long term stability of articaine and minimizediscomfort to the patient when applied topically to the surface of theeye. The pH is generally in the range of about pH 4.5 to about pH 7.0. Aparticularly suitable pH of an articaine composition is about pH 4.5 toabout pH 5.5 for compositions containing amounts of articaine greaterthan about 4.0% and typically greater than about 6.0% w/v. One suitablecomposition containing at least 7.0% w/v or higher has a pH range ofabout pH 4.5 to about pH 5.5 and found to exhibit long term storage ofthe articaine in the composition for several months at room temperature.The compositions having a pH 5.0 or below provide long-term storage ofthe articaine to inhibit decomposition of articaine during storage.Compositions having about pH 4.5 to about pH 5.0 provide excellentlong-term storage without discomfort to the patient when topicallyapplied.

The topical ophthalmic anesthetic composition containing articaineincludes a buffer to adjust, modify, and/or maintain the pH andosmolality within a desired range to stabilize articaine withoutinteracting with articaine or causing degradation of the articaine inthe composition during storage. The buffer and other excipients in thetopical ophthalmic anesthetic composition enable higher concentrationsof articaine of 7.5% w/v and up to 8.5% w/v or higher withoutdecomposition of the articaine while maintaining the articaine insolution or suspension with minimal discomfort to the patient when thecomposition is administered topically to the surface of the eye. Thebuffer according the embodiments of the composition provides a stablecomposition at higher concentrations of articaine that are not presentin the prior compositions.

Articaine is able to inhibit the growth of certain bacteria, such asPseudomonas aeruginosa, Proteus mirabilis, Staphylococcus aureus, andEscherichia coli. The mechanism of antibacterial action is understood asbeing mediated by inhibition of cell wall synthesis or distortion ofcytoplasmic membrane.

The topical ophthalmic anesthetic composition as described is a stablecomposition that can be applied topically to the surface of the eyewithout adverse effects. The topical ophthalmic anesthetic compositioncan be applied in drop form directly to the surface of the eye. Thetopical ophthalmic anesthetic composition contains an amount ofarticaine that is able to provide an anesthetic effect to the eye by asingle dosage to the surface of the eye. The dosage is selected based onthe final concentration of articaine and other buffers, pH adjustingagents and other excipients in the composition to provide the desiredanesthetic effect. In one embodiment, the topical composition is appliedas a single dosage of a single drop of about 2 μl to about 30 μl at anarticaine concentration of about 8.0 mg/g of the anesthetic composition.One example of a drop size is about 15 μl. In one embodiment a suitabledosage is about 0.5 μl for the ophthalmic composition containing about8% w/v of articaine. In other embodiments, the articaine composition canbe administered by about 3-5 drops to the surface of the eye to providea dosage of about 20 μl or units to about 100 μl. In another embodiment,the topical ophthalmic anesthetic composition is applied at a dosage of3-8 drops, typically about 3-5 drops to the surface of the eye, toprovide a dosage of about 40 μl to about 80 μl of the compositioncontaining about 8% w/v articaine.

In a first embodiment of the topical anesthetic composition, thecomposition is an aqueous mixture containing a buffer and has a pH rangeof about pH 3.5 to about pH 7.0. The composition can have a dissolvedoxygen content of less than 2 ppm to stabilize the composition and toinhibit oxidation of articaine and/or other compounds in thecomposition. A particularly suitable pH range is about pH 4.5 to aboutpH 5.0 and an osmolality of about 580 to about 630 mOsm/kg. A suitablearticaine amount in the composition is about 7.0% to about 8.5% w/varticaine. The buffer in this embodiment can be a complex obtained froma mixture of boric acid and D-mannitol. The borate/mannitol complexformed from boric acid and D-mannitol has been found to stabilizearticaine and provide long storage stability of articaine in thecomposition at articaine concentrations greater than about 4% w/v andgreater than 7% w/v with a pH in the range of pH 4.5 to pH 5.0 withoutirritation to the eye when applied topically to the surface of the eye.Without intending to be bound by a specific theory, the borate componentof the borate/mannitol complex is understood as providing a suitablestabilizing effect to the articaine that enables a stable articaineconcentration of at least 7% w/v at a pH less than about pH 5.5. Thebuffer provides a stable pH range of about pH 4.5 to about pH 5.0 forarticaine enabling concentrations of articaine greater than 4% w/vwithout irritation to the eye.

In other embodiments, the buffer can be obtained from another source ofa borate anion, such as a borate salt. Examples of borate salts includesodium borate, calcium borate, magnesium borate, manganese borate andothers. The buffer complex can be obtained from the reaction mixture ofboric acid, citric acid, or mixtures thereof, and a sugar alcohol, suchas D-mannitol, sorbitol, and mixtures thereof. The borate/mannitolcomplex has been found to be particularly suitable for stabilizing highconcentrations of articaine, such as 8% w/v articaine or higher. Aborate salt and/or a citrate salt can be used as a source of borateand/or citrate to the reaction mixture to form the borate/mannitolcomplex, a citrate/mannitol complex and/or borate/citrate/mannitolcomplex.

The anesthetic composition in one embodiment includes the buffer complexobtained from boric acid and a sugar alcohol, such as D-mannitol, wherethe buffer complex is a borate/mannitol complex. The ratio or relativeamounts of the boric acid and alcohol sugar are selected based on thedesired pH, osmolality, compatibility with articaine, and the articaineconcentration in the anesthetic composition. The buffer can be obtainedfrom a mixture of boric acid in an amount of about 13 wt % to about 15wt % and D-mannitol in an amount of about 85 wt % to about 87 wt % basedon the total weight of the boric acid and D-mannitol mixture. The bufferin one embodiment can be obtained from a mixture of about 14 wt % boricacid and about 86 wt % D-mannitol based on the combined weight of theboric acid and D-mannitol. Boric acid in the topical ophthalmicanesthetic composition forming the borate/mannitol complex can be inamount of about 0.08% w/v to about 0.10% w/v and D-mannitol included inan amount of 0.50% w/v to about 0.60% w/v based on the total volume ofthe topical ophthalmic anesthetic composition.

The amount of the borate/mannitol complex included in the topicalophthalmic anesthetic composition is based on the amount of articaine inthe final composition to stabilize the articaine and provide the longterm storage of the ophthalmic composition. The amount of theborate/mannitol complex can be about 0.4% w/v to about 0.75% w/v basedon the total volume of the ophthalmic composition. In one embodiment,the amount of the borate/mannitol complex can be about 0.5% w/v to about0.75% w/v based on the total volume of the ophthalmic composition. Inother embodiments, the borate/mannitol complex is included in the finalophthalmic composition is an amount of about 6.5 parts by weight toabout 7.5 parts by weight based on 100 parts by weight of articaine inthe ophthalmic composition.

In other embodiments, the buffer complex is produced from an acid, suchas boric acid, citric acid, and mixtures thereof and a sugar alcohol,such as mannitol, sorbitol and mixtures thereof where the ratio of theacid to sugar alcohol can range from about 1:10 to 10:1. In theembodiment described, the amount of the sugar alcohol is greater thanthe amount of the acid, i.e., an acid to sugar alcohol in the range of1:3 to 1:10. A boric acid to mannitol ratio can be about 1:3 to about1:7 by weight. In one embodiment, the ratio of the boric acid tomannitol can be about 1:4 to about 1:6 by weight. A further example of asuitable boric acid to mannitol ratio can be about 1:4.5 to about 1:5.5by weight. Another example of a suitable buffer complex is aborate/citrate/mannitol complex obtained from a mixture of boric acid,citric acid and mannitol.

Other buffer and antioxidant components in the embodiment can beincluded in addition to boric acid and D-mannitol. An example of anadditional buffer and/or antioxidant compound include an acetate anion,such as sodium acetate trihydrate. The additional buffer and/orantioxidant compound can be included in an amount of about 0.3% to about0.5% w/v based on the total volume of the topical ophthalmic anestheticcomposition. In this embodiment, sodium acetate trihydrate is includedin an amount of 0.33% w/v based on the total volume of the topicalophthalmic anesthetic composition. Sodium acetate can be included incombination with a complex from boric acid and D-mannitol in an amountof about 33 wt % to about 35 wt % and typically about 34 wt % based onthe combined weight of the buffer including boric acid, D-mannitol, andsodium acetate.

Other excipients in the topical ophthalmic anesthetic compositioninclude pH adjusting agents or antiseptic compounds. Acetic acid, suchas glacial acetic acid, is an example of a suitable acid for adjustingthe pH and having antiseptic properties that is compatible with thetopical ophthalmic anesthetic composition containing articaine. Aceticacid, typically added as glacial acetic acid, is included in an amountof about 0.05% w/v to about 0.07% w/v based on the total volume of theanesthetic composition. Other excipients can include a chelating agent,such as disodium edetate dihydrate.

The topical ophthalmic anesthetic composition in one embodiment includesarticaine in amounts of about 4.5% to about 8.5% w/v, a complex formedfrom boric acid and D-mannitol as a buffer, sodium acetate, acetic acid,disodium edetate, and the balance water. In a suitable embodiment, thetopical ophthalmic anesthetic composition contains about 7.5% to about8.5% w/v articaine, a complex obtained from about 0.08% w/v to about0.10% w/v boric acid and about 0.5% w/v to about 0.6% w/v D-mannitol,about 0.30 to 0.36% w/v sodium acetate, about 0.05% w/v to about 0.07%w/v glacial acetic acid, about 0.05% w/v to about 0.07% w/v disodiumedetate dihydrate, based on the total volume of the composition. Thetopical composition can have an osmolality of about 580 to 630 mOsm/kg.In a further embodiment, the composition consists essentially ofarticaine, a buffer obtained from boric acid and D-mannitol, sodiumdiacetate, acetic acid, disodium edetate, and water.

Another suitable example of a suitable topical ophthalmic compositionincludes about 7.5% to about 8.5% w/v articaine based on the totalvolume of the composition, a borate/mannitol complex buffer, and anarticaine stabilizer compound, where the composition has a pH of aboutpH 4.5 to pH 7.0, an osmolality of about 500 to 700 mOsm/kg, andviscosity of about 700 to 850 cp.

In another embodiment, the topical ophthalmic anesthetic composition isan aqueous composition containing at least 4% w/v articaine, and abuffer that is non-reactive with articaine to provide a stablecomposition without degradation of the articaine and with minimalirritation to the eye. In other embodiments, the topical ophthalmicanesthetic composition contains articaine in amounts of about 5.0% to8.5% w/v based on the total volume of the composition. In still furtherembodiments, the topical ophthalmic anesthetic composition containsarticaine in an amount of at least about 8.0% w/v based on the totalvolume of the composition.

The buffer is selected to be compatible with articaine to avoidreactions with articaine, inhibit decomposition of articaine duringstorage, and provide a pH to stabilize the articaine and provide thedesired concentration of articaine in the composition with minimalirritation to the eye. The buffer stabilizes the articaine bystabilizing the reactive groups, such as the amino group. Stabilizersinclude compounds that inhibit oxidation of the reactive groups onarticaine by oxygen and/or oxo radicals. Sodium sulfite is an example ofa stabilizer to inhibit oxidation in certain embodiments. Otherantioxidants include sodium EDTA, sodium metasulfite, and ascorbic acid.The topical ophthalmic anesthetic composition in an embodiment has a pHof about pH 4.5 to about pH 7.0 and an osmolality of 280 to 320 mOsm/kg.In other embodiments, the buffer contains compounds to maintain a pH inthe topical ophthalmic anesthetic composition of about pH 5.0 to pH 7.0.The buffer can also produce a composition having about pH 4.7 to aboutpH 5.5 depending on the composition and the buffer. In anotherembodiment, the topical ophthalmic anesthetic composition can have a pHof at least a pH 5.4. The pH can depend on the buffers and theconcentration of articaine in the topical ophthalmic anestheticcomposition.

The topical ophthalmic anesthetic composition can be prepared by methodsor procedures to obtain the composition suitable for topical applicationto the eye. In the embodiments containing the buffer complex, thecomplex is generally prepared before mixing or combining with thearticaine to provide the stabilizing effect to the articaine. A processfor producing the composition in one embodiment prepares the complex inan aqueous medium first by adding the acid component to water to form anacid solution. The acid compound can be boric acid, citric acid, ormixtures thereof. The sugar alcohol, such as mannitol, sorbitol, ormixtures thereof is then added to the acid solution and allowed to reactfor sufficient time to form the complex, such as a borate/mannitolcomplex. The excipients then are added to the solution of theborate/mannitol complex to obtain the desired pH and final composition.Examples of excipients include the addition sodium acetate trihydrate tothe solution of the borate/mannitol complex until dissolved. Aceticacid, such as glacial acetic acid, is added to acidify the solution.EDTA dihydrate then is added to obtain the desired pH. The articaine HClsalt is added and dissolved to obtain the articaine composition toobtain the ophthalmic composition having the desired articaineconcentration.

Various methods can be used to administer and anesthetize the eye of apatient using the topical ophthalmic anesthetic articaine composition.In one embodiment, the aqueous topical anesthetic composition isadministered directly to the surface of the eye in an effective amountto provide sufficient anesthesia to the eye. A topical ophthalmicanesthetic composition containing 7% w/v or more can be administereddrop-wise to the surface of the eye to provide sufficient anesthesia tothe eye. A suitable dosage is typically about 30 μl for a compositioncontaining at least about 7% w/v articaine. Compositions containing lessthan 7% w/v articaine may require a larger dosage or repeated dosages toadminister an effective amount of articaine to the surface of the eye toachieve the desired anesthetic effect.

In a further embodiment the buffer can be borate/mannitol (pH 6.0),citrate (pH 5.5), acetate (pH 5.5), or phosphate (pH 6.5, 7.0, 7.5). Thebuffer can be included in an amount of not greater than 25 mM and canprovide a pH less than pH 7.0 and generally less than pH 5.5. In otherembodiments, the buffer can include a mixture of sodium hydroxide andhydrochloric acid. Other suitable buffers include monobasic sodiumphosphate and dibasic sodium phosphate.

The topical anesthetic composition can also include optional lubricantsand viscosity modifiers. Examples of other additives and excipients caninclude polyethylene glycol, glycerol, sodium sulfite, sodiummetasulfite, cetyl alcohol, hydroxypropyl B-cyclodextrin, polaxmer,tyloxapol, and ascorbate.

Exemplary embodiments of the present disclosure provide a topicalophthalmic anesthetic comprising a unique formulation with the desiredarticaine concentration, pH, viscosity, dissociation constant, andadditives such as antioxidants, buffers, viscosifiers, such asmethylcellulose, to achieve efficacy and safety. Exemplaryimplementations the present disclosure include formulations comprising aliquid, gel, ointment, or in an encapsulated form.

Further exemplary implementations of the present disclosure can takeinto consideration the practicality of the manufacture of theformulations according to exemplary embodiments. For example, in thecase of exemplary implementations comprising an ophthalmic solution,varying amounts of methylcellulose may be added to increase viscosityand thereby increase contact time with the external ocular surface,increasing the efficacy of articaine. Suitable viscosity modifyingagents do not negatively interact with or destabilize articaine. Otherviscosity modifiers include polyvinyl alcohols and hydroxypropyl methylcellulose.

Another exemplary implementation of the topical ophthalmic anestheticcomposition includes articaine in an amount of about 4% to about 8.0%w/v supplied with epinephrine 1:100,000 as a sterile composition fortopical application by an ophthalmic drop. The composition can beapplied topically to treat the eye in preparation for an intravitrealinjection. The topical composition can be applied as a single drop or byseveral applications to provide the desired anesthetic effect in theeye. The topical ophthalmic composition can be applied as a drop by 3 to6 applications with a time of 3-5 minutes between applications. Inanother embodiment, the topical composition can be applied oradministered as a single drop and reapplied after 2-5 minutes 3-5 times.

Another exemplary embodiment provides a topical ophthalmic anestheticcomposition comprising articaine as a topical ophthalmic anestheticincluding 4% to 8.0% w/v articaine having a pH of about pH 4.5 to aboutpH 5.5, and a pKa of about 7.0 to about 8.5. An example of the aqueousanesthetic composition includes about 4% w/v to about 5 w/v articainehaving a pH 5.5, a pKa 7.8, a viscosity of 20-25 cp (centipoise),osmolality of 275-1171 mOsms/kg, tonicity of 0.5%-5.0%, NaOH buffer, andHCl buffer.

A further example of a suitable aqueous topical ophthalmic compositionincludes about 4% w/w to about 13% w/v articaine and generally at leastabout 7% w/v articaine, sodium phosphate monobasic monohydrate, dibasicsodium phosphate, a viscosity enhancer, such as hydroxypropylmethylcellulose and polyethylene glycol, with a pH of about pH 6.0 to about pH7.0. An example of the anesthetic composition includes 80 mg/g articaineHCl, 1.373 mg/g sodium phosphate monobasic monohydrate, 1.413 mg/gsodium phosphate dibasic anhydrous, 8.1 mg/g hydroxypropylmethylcellulose, 4 mg/g PEG400, and where the composition has a pH of pH 6.0to pH 7.0, a viscosity of 743-803 cp, and an osmolality of 517 mOsm/kg.

The topical composition containing 4% w/v articaine applied in one ortwo doses did not provide a complete anesthetic effect. However, it wasobserved that 3 or more doses of one drop per application at intervalsof 3-5 minutes resulted in effective anesthesia. In addition, patientsdid not complain of burning, itching, redness, or other manifestationsof ocular surface irritation, which are commonly experienced withcurrently used topical ophthalmic anesthetics.

A feature of the disclosure is a method of providing anesthesia to theeye by topical application or delivery to the eye by the topicalanesthetic ophthalmic composition. The anesthetic is administeredtopically prior to surgery, such as prior to intraocular injections,pars plana vitrectomy, and the like.

Typically, a physician administers an injectable anesthetic toanesthetize the eye, then must wait a suitable period of time for theanesthetic to take effect before beginning a procedure. A benefit of atopical approach according to exemplary implementations of the presentdisclosure is the ease of administering the anesthetic by applying thecomposition topically without the need to inject an anesthetic into theeye.

The efficacy and safety of articaine is well established for use as ananesthetic by injection, such as in the dental industry. Articaine HCl,has the molecular formula 4-methyl-3(2-[propylamino]proprioamido)-2-thiophenecarboxylic acid, methyl esterhydrochloride with a molecular weight of 320.84 g/mol, highly proteinbound, and has a pKa of 7.8. Articaine is an amide-containing anestheticthat contains a thiophene ring and an additional ester group. Thethiophene ring provides an increase in the lipid solubility of articainecompared to other amide-containing anesthetics. Articaine is highlydiffusible and penetrates tissue and bone effectively when administeredby injection. The presence of the amide group and the ester linkageminimizes a toxic reaction as the biotransformation occurs both inplasma (hydrolysis by plasma esterase) and hepatically (microsomalenzymes). The metabolism is initiated by hydrolysis of the ester groupsto generate free carboxyl group. Articainic acid is the primarymetabolite. Additional inactive metabolites have been detected in smallamounts. Five to ten percent is renally excreted unchanged and 89% isexcreted as the metabolites. An injectable form of articaine is commonlyused as an anesthetic in dentistry.

Articaine acts by inhibiting nerve conduction through the blockade ofsodium channels in tissue. Articaine acts by reversibly binding to thealpha subunit of the voltage gated sodium channels within the nerve.This reduces sodium influx so that the threshold potential of the nervewill not be reached, halting impulse conduction. Articaine is a shortacting, rapid onset of action, tissue penetrating local anesthetic.Articaine has been used in combination with epinephrine in injectablecompositions to cause local vasoconstriction, increasing the absorption,and increasing the duration of action. In injectable applications,articaine is typically used at a 4% w/v concentration. Commerciallyavailable injectable formulations include articaine hydrochloride (4%)with epinephrine in an amount of 1:1000,000 (0.01 mg/ml).

No serious adverse reactions have been reported for commerciallyavailable injectable forms of articaine. Allergic reactions are rare,although sodium bisulfite as a preservative in some commercialpreparations may cause allergic reactions such as edema, urticarial,erythema, and anaphylactic shock in some patients. Articaine is notassociated with an increase in methemoglobin. Articaine iscontraindicated in patients allergic to amide-containing anesthetics andmetabisulfites. Articaine is not contraindicated in patients with sulfaallergy in that there is no cross allergenicity between thiol group ofthe articaine thiophene ring and the sulfonamides.

The following examples are provided to demonstrate suitable compositionsand methods but are not intended to be limiting of the scope of thisdescription.

Example 1

Two subparts of one study were conducted on Dutch Belted rabbits,namely, an ocular tolerability study followed by an ocularbiodistribution study.

In the ocular tolerability study, a total of twelve male Dutch Beltedrabbits divided randomly into four groups, were administered a placeboof phosphate buffered saline (PBS) or articaine at 4%, 8%, or 12%respectively. Doses were administered via bilateral topicaladministration (two drops of 35 μL/eye). Rabbits in the dosetolerability study were observed for 24 hours post treatment for anysign/symptoms of adverse drug effects. Ophthalmic examinations wereperformed on dose tolerability animals (Groups 1 through 4) predose andat 5, 10, and 20 minutes, and at 1, 2, 4, and 24 hours post the secondeye drop administration in each eye using the modified Hackett-McDonaldScoring System. Following the modified Hackett-McDonald Scoring, localanesthetic effect was monitored in each eye by Cochet-Bonnetesthesiometry predose and at approximately 5, 10, and 20 minutes, and 1hour following administration of the second eye drop in each eye.Articaine eye drops were well tolerated in all animals at concentrationsup to 12% w/v and no treatment related adverse effects were noted.Topical ocular administration of articaine provided an anesthetic effectout to 20 minutes postdose with no notable tolerability issues.

In the ocular biodistribution study, after a minimum of 72 hoursfollowing the completion of the ocular tolerability study, the twelverabbits were re-assigned to Group 5 for the ocular biodistributionstudy. Group 6 was added and consisted of 3 naïve rabbits. Group 6 wasincluded to evaluate the potential carryover effect of articaine over a72 hour period post treatment. Group 5 and 6 animals were administeredarticaine at 8% and 12% w/v, respectively. Doses were administered viabilateral topical administration (two drops of 35 μL/eye). Group 5animals were sacrificed at 10 minutes, and 1, 4 and 8 hours posttreatment (N=3 at each time point). Group 6 rabbits were sacrificed at24, 48 and 72 hours post treatment (N=1 at each time point). Just priorto sacrifice blood samples were collected from each animal. Animals werethen euthanized and aqueous humor, conjunctivas (palpebral and bulbar),lens, cornea, vitreous humor, iris-ciliary body [ICB], optic nerve,lacrimal gland, retina, and choroid were collected. Plasma, aqueoushumor, conjunctivas (palpebral and bulbar), lens, cornea, ICB, choroid,and lacrimal gland tissues were analyzed for concentrations of articaine(active parent) and articainic acid (inactive metabolite), and theremaining tissues stored frozen for possible future analysis. Articaineconcentrations displayed a typical profile following topical ocularadministration of the 8% formulation; highest at the earliest time point(0.167 hours) examined and then decreasing at the later time points (1,4, and 8 hours). Articainic acid concentrations followed a similarprofile in all matrices with the exception of aqueous humor in which theconcentration increased from 0.167 hours to 1 hour, and then decreasedat the later time points (4 and 8 hours). Low residual concentrations ofarticaine and articainic acid following 12% articaine topical ocularadministration were detected in all ocular matrices examined at 24, 48,and 72 hours postdose (with the exception of articainic acid in thechoroid). Articaine concentrations were higher than articainic acid inall ocular matrices with the exception of the cornea. As expected, Tmaxfollowing topical ocular administration of articaine was noted at thefirst timepoint (0.167 hours) examined in all ocular matrices andplasma. Cmax for articaine was highest in the iris-ciliary body (294,000ng/g) followed by the palpebral conjunctiva (131,000 ng/g), choroid(103,000 ng/g), bulbar conjunctiva (94,000 ng/g) and cornea (53,500ng/g). Plasma Cmax was 457 ng/mL, the lowest of all matrices examined.AUC values denoting exposure of the matrices to articaine generallyfollowed the same order of highest (i.e., iris-ciliary body) to lowest(i.e., plasma) as seen in the Cmax values. T1/2 (half-life) of articainein the ocular matrices ranged from 1.95 to 3.83 hours with the exceptionof the palpebral conjunctiva with T1/2 of 6.31 hours, likely related tothe topical dose pooling in the lower eyelid following dosing. T1/2 ofarticaine in the plasma was approximately 0.5 hours. Cmax for articainicacid was highest in the palpebral conjunctiva (71,100 ng/g), cornea(53,500 ng/g), bulbar conjunctiva (29,100 ng/g), and iris-ciliary body(12,600 ng/g). Plasma Cmax was 217 ng/mL, the lowest of all matricesexamined. AUC values denoting exposure of the matrices to articainicacid generally followed the same order from high to low as articaine butwere substantially less than those for articaine with the exception ofthe cornea and plasma. As noted by the ratio of AUC0-last articainicacid over AUC0-last articaine, the ratio was approximately 2 for bothcornea and plasma, indicating greater exposure to articainic acid thanto articaine in these two matrices. In all other matrices the ratio was<0.7. T1/2 (half-life) of articainic acid in most of the ocular matricesranged from 1.70 to 3.29 hours. T1/2 of articainic acid in the plasmawas approximately 1.5 hours.

In summary, topical ocular administration of articaine provided ananesthetic effect out to 20 minutes postdose with no notabletolerability issues. Articaine and articainic acid were detected in allocular matrices examined with the highest exposure found in theiris-ciliary body, the bulbar and palpebral conjunctiva, and cornea.Rapid metabolism of articaine to articainic acid is expected given thepresence of esterase activity in the ocular tissues. Systemic exposure,as indicated by plasma AUC, was minimal.

The objectives of this study were to determine the tolerability ofplacebo and Articaine HCl ophthalmic solutions at concentrations of 4,8, and 12% (w/v) following topical eye drop administration, and todetermine the ocular pharmacokinetics and biodistribution of articaineand articainic acid following topical eye drop administration of 8%Articaine HCl ophthalmic solution. The rabbit is a standard non-rodentspecies used in preclinical pharmacokinetic studies, including ocularpharmacokinetics, of new chemical entities and different test articleformulations. The number of animals is considered an appropriate numbernecessary to properly perform this tolerability and ocularbiodistribution study and accounts for variability among animals as wellas allows for the generation of descriptive statistical analysis. Thetopical route was selected as this is the intended route ofadministration in humans. The ocular formulation dose levels selected bythe Sponsor were designed to achieve therapeutic ocular tissueconcentrations of the test article. The single dose of the test articleis common for determination of pharmacokinetics.

A study with an approved aqueous articaine formulation was conducted inhumans and very favorable initial results corroborate the results of therabbit study.

Example 2

A topical ophthalmic anesthetic composition was prepared containing thearticaine HCl at a concentration of 8.0% w/v as shown in Table 1.

TABLE 1 Composition for 1L Batch Concentration, Excipients % w/v AmountArticaine, HCl salt 9.02% * 90.20 ± 0.90 g Boric acid 0.09% 0.913 ±0.010 g D-Mannitol 0.55% 5.500 ± 0.055 g Sodium acetate, 0.33% 3.332 ±0.033 g trihydrate Glacial Acetic acid 0.06% 0.630 g ± 0.010 g EdetateDisodium, 0.06% 0.550 ± 0.010 g dihydrate Water for Injection Initial +QS Initial Qty: 850.0 ± 8.5 g Batch Size (L) 40 (1 L amount) grams kgArticaine, HCl salt 90.200 3608.000 3.608 Boric acid 0.913 36.520 0.037D-Mannitol 5.500 220.000 0.220 Sodium acetate, 3.332 133.280 0.133trihydrate Glacial Acetic acid 0.630 25.200 0.025 Edetate Disodium,0.550 22.000 0.022 dihydrate Water for Injection 850.000 34000.00034.000 * Equivalent to 8.0% of Articaine, as the free base

The composition was prepared by adding the boric acid to a mixing vesselcontaining a volume of water until dissolved. Mannitol was then addedand mixed until dissolved and stirred to form the borate/mannitol buffercomplex. The sodium acetate trihydrate was then added and stirred untildissolved followed by the addition of glacial acetic acid. The EDTAdihydrate was added to obtain a pH of about pH 4.5 to pH 5.2. Thearticaine HCl was added and stirred until dissolved. The resultingcomposition had a pH of pH 4.7 to pH 4.9, and an osmolality of 580 to630 mOsm/kg.

Example 3

The topical ophthalmic compositions were prepared having thecompositions shown in Table 2 below. Systane and Systane+8% ArticaineHCl are included here solely because they were used as viscositycomparatives, but are not otherwise part of the formulation study.

TABLE 2 Formulation Composition Formulations (mg/g) compositionComposition A B C D E F Articaine  80  80  80  80    80  80 HCl¹ Sodium 9  7.5  6  4.5 — — Chloride Sodium —  1.37  1.37  4.5    1.37³  1.37³Phosphate Monobasic Monohydrate Sodium — — — — —  1.41³ PhosphateDibasic Anhydrous HPMC  8.1  8.1  8.1  8.1    8.1  8.1 K100 PremiumPEG400  4  4  4  4    4  4 Final pH  6.96  6.94  7.00  6.91    4.85 6.06 Viscosity 779-827 752-792 715-801 761-799 ~700 743-803 (cp)Osmolality 610 767 725 700   507 517 (mOsm/kg) ¹Amount equivalent toArticaine free base ²Two separate measurements ³10 mM concentrations

The formulations C and F were evaluated for the stability of theformulations over a period of 8 weeks in containers stored at 5° C., 25°C., and 45° C.

The results of the storage at 5° C., 25° C., and 45° C. showedacceptable impurity levels, stable pH, viscosity, and osmolality.Formulation F was demonstrated to be useful based on degradation levels.PEG400 appears to be highly reactive with articaine. A buffer with aslow a pH as possible and still tolerable to the patient is indicated. Aboric acid/mannitol buffer achieved the needed stability.

In one embodiment, the composition consisted of 35 mM acetate, pH 4.8,with 15 mM borate-mannitol complex, and 0.055% EDTA (disodium, dehydratesalt). The acetate can be obtained from acetic acid, sodium acetate ormixtures thereof. This formulation exhibited a stable pH, and alsodemonstrated a low hydrolysis rate of −0.04% articainic acid formed perweek, over a 4-week period at 40° C. (1.53% total over 8 weeks), andhydrolysis at a rate of 0.061%/week at 25° C. (0.49% total over 8weeks). This is over 4 times slower than previously known formulation.

Several aspects of the process were determined in experiments at a 100-gscale and then scaled up to 500-g to confirm.

The borate-mannitol complex, which is much more acidic than boric acid(pKa 9.14) alone, forms readily when these two excipients are combinedin the absence of other excipients or buffers, resulting in a pH ofaround 4.2. In terms of order of addition, these two excipients areadded first and the formulation allowed to mix to allow the complex tofully form.

A suitable molar ratio of sodium acetate to acetic acid is 70:30 (24.5mM to 10.5 mM), in order to avoid the need for any pH adjustment afterdissolution of the Articaine HCl. When this ratio is used, the final pHafter addition of 90.2 mg/mL of Articaine HCl (equal to 80 mg/mL ofArticaine as free base) was reproducibly around pH 4.80±0.05.

The process was easily scaled up to 500 mL, with final pH of 4.80 andfinal osmolality of 622 mOsm/kg. Later, it was also scaled up to 1 L,and the final formulation had a pH of 4.85 and an osmolality of 597mOsm/kg, after filtration.

The drug products prepared in the process development experiments werethen used in the filtration studies to confirm whether PVDF was anappropriate filter material for this formulation, and to determine theappropriate filter size.

There was no indication of API binding to the PVDF filter material, asthe concentration of drug both before and after filtration wasconsistent, with no loss of concentration in the early aliquots.Therefore, no discard volume is required.

The Vmax study showed very little decrease in flow rate over time,indicating that filter fouling is not an issue with this formulation,and that a relatively small filtration area can be used to filter a 1-Lbatch of drug product. Therefore, filter size can be chosen mostly onthe basis of the needed flow rate, which can also be adjusted by the useof higher pressure.

While the present disclosure has been shown and described with referenceto certain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentdisclosure.

Publications cited throughout this document are hereby incorporated byreference in their entirety. Each feature described herein, and eachcombination of two or more of such features is included within the scopeof the present disclosure provided that the features included in suchcombination are not mutually exclusive.

The invention claimed is:
 1. An aqueous topical ophthalmic anestheticcomposition comprising: articaine in an amount of about 4.0% w/v toabout 13.0% w/v based on the volume of the composition; and a buffer inan amount to provide a pH of about pH 3.5 to about pH 7.0, where saidbuffer is non-reactive with and stabilizes articaine to inhibitdegradation of said articaine during storage, where said composition hasan osmolality of 275 to 1171 mOsm/kg to facilitate topical applicationfor ophthalmic anesthesia, and where said buffer is present in an amountto stabilize and inhibit degradation of said articaine.
 2. Thecomposition of claim 1, wherein said composition has a pH of about pH4.5 to about pH 5.5, and where said buffer comprises a complex obtainedfrom a citrate, acetate or mixture thereof and a sugar alcohol selectedfrom the group consisting of mannitol, sorbitol and mixtures thereof. 3.The composition of claim 1, wherein said composition comprises about7.5% w/v to 8.5% w/v articaine and said composition has a pH of about pH4.5 to about pH 5.0.
 4. The composition of claim 1, wherein saidcomposition contains at least about 7.0% w/v articaine and has a pH ofabout pH 4.5 to about pH 5.0.
 5. The composition of claim 1, whereinsaid buffer comprises a borate/mannitol complex obtained from a borateand D-mannitol.
 6. The composition of claim 5, wherein saidborate/mannitol complex is included in an amount of about 0.5% w/v toabout 0.75% w/v based on the volume of the composition.
 7. Thecomposition of claim 5, wherein said borate/mannitol complex is includedin an amount of about 6.5 parts by weight to about 7.5 parts by weightbased on 100 parts by weight of articaine in the composition.
 8. Thecomposition of claim 5, wherein said borate/mannitol complex is obtainedfrom a borate/mannitol ratio of about 1:3 to about 1:7 by weight.
 9. Thecomposition of claim 5, wherein said composition further includes sodiumacetate, acetic acid, and disodium edetate.
 10. The composition of claim1, wherein said composition comprises at least about 7.0% w/v articaineand said buffer comprises a complex of boric acid and D-mannitol in anamount to provide a pH of about pH 4.5 to about pH 5.0 and saidcomposition further comprises sodium acetate, acetic acid, and disodiumedetate.
 11. The composition of claim 4, wherein said articaine ispresent in an amount of at least about 7.0% w/v, and said boric acid andD-mannitol complex is obtained from about 0.08% w/v to about 0.10% w/vboric acid and about 0.50% w/v to about 0.6% w/v D-mannitol based on thetotal volume of the composition.
 12. The composition of claim 1, whereinsaid composition comprises at least about 8.0% w/v articaine, a buffercomplex obtained from about 0.08% w/v to about 0.10% w/v boric acid andabout 0.5% w/v to about 0.60% w/v D-mannitol, about 0.3 to 0.36% w/vsodium acetate, about 0.05% w/v to about 0.07% w/v disodium edetate, andthe balance water, and where said composition has an osmolality of about280 to 320 mOsm/kg and the amounts are based on the total volume of thecomposition.
 13. The composition of claim 1, wherein said compositioncomprises about 4% w/v articaine, and said buffer comprises NaOH andHCl, and said composition has a pH of about pH 5.5, a pKa of about 7.8,a viscosity of about 20-25 cp, an osmolality of about 275 to 1171mOsm/kg, and a tonicity of about 0.5 to 5.0%.
 14. The composition ofclaim 1, wherein said composition comprises 80 mg/g articaine HCl, 1.373mg/g sodium phosphate monobasic monohydrate, 1.413 mg/g sodium phosphatedibasic anhydrous, 8.1 mg/g hydroxypropylmethyl cellulose, 4 mg/gPEG400, and where said composition has a pH of pH 6.0 to pH 7.0, aviscosity of 743-803 cp, and an osmolality of 517 mOsm/kg.
 15. Anaqueous topical ophthalmic anesthetic composition comprising: articainein an amount of about 4.0% to about 13% w/v based on the volume of thecomposition; and a buffer in an amount to provide a pH of pH 3.5 to 7.0to inhibit irritation to an ocular surface and to stabilize articaineduring storage, and where said buffer is a complex obtained from a boricacid or a boric acid salt and a sugar alcohol in an amount to maintainsaid articaine in solution or suspension and inhibit degradation of saidarticaine during storage.
 16. The aqueous ophthalmic anestheticcomposition of claim 15, wherein said buffer is a borate/mannitolcomplex in an amount of about 6.5 parts by weight to about 7.5 parts byweight based on 100 parts by weight of articaine in the composition. 17.The aqueous ophthalmic anesthetic composition of claim 16, wherein saidborate/mannitol complex is obtained from a borate/mannitol ratio ofabout 1:3 to about 1:7 by weight.
 18. The aqueous ophthalmic anestheticcomposition of claim 17, further comprising sodium diacetate, aceticacid, and disodium edetate.
 19. A method of providing anesthesia to theeye, the method comprising the step of topically applying thecomposition of claim 1 to the surface of the eye of a patient in anamount effective to anesthetize the eye of the patient.
 20. The methodof claim 19, wherein said composition comprises articaine in an amountof at least about 5.0%, said buffer complex obtained from about 0.08%w/v to about 0.10% w/v boric acid and about 0.50% w/v to about 0.6% w/vD-mannitol based on the total volume of the composition.
 21. The methodof claim 19, wherein said composition comprises at least about 7.5% w/varticaine; a buffer including a complex obtained from boric acid andD-mannitol in an amount that is non-reactive with articaine; sodiumacetate; acetic acid; disodium edetate, and the balance water, and wheresaid composition has a pH of about pH 4.5 to about pH 5.5.
 22. Themethod of claim 19, wherein said composition comprises at least about 7%w/v articaine.
 23. The method of claim 22, wherein said composition hasa pH of about pH 4.5 to about pH 5.0.
 24. The method of claim 19,wherein said formulation comprises 4% w/v articaine, has a pH 5.5, a pKaof 7.8, a viscosity of 20-25 cp, an osmolality of 275-1171 mOsms/kg, atonicity of 0.5%-5.0%, a NaOH buffer, and a HCl buffer.
 25. The methodof claim 19, wherein said composition comprises 80 mg/g articaine HCl,1.373 mg/g sodium phosphate monobasic monohydrate, 1.413 mg/g sodiumphosphate dibasic anhydrous, 8.1 mg/g hydroxypropylmethyl cellulose, 4mg/g PEG400, and where said composition has a pH of pH 6.0 to pH 7.0, aviscosity of 743-803 cp, and an osmolality of 517 mOsm/kg.
 26. A methodof producing the composition of claim 1, comprising the steps of: mixingan acid or salt thereof and a sugar alcohol in a solution to form abuffer complex; adjusting the pH to about 3.5 to about pH 7.0; andadding articaine to the resulting solution in an amount to obtain saidcomposition having about 4.0% w/v to about 13% w/v based on the volumeof the composition, and stabilizing said composition by including anamount of said buffer complex to maintain said articaine in solution orsuspension and to inhibit degradation of said articaine during storage.27. The method of claim 26, wherein said acid is selected from the groupconsisting of acetic acid, citric acid, and mixtures thereof, and saidsugar alcohol is selected from the group consisting of D-mannitol,sorbitol, and mixtures thereof.
 28. The method of claim 26, wherein saidacid or salt thereof is a borate salt and said sugar alcohol isD-mannitol, and said complex is a borate/mannitol complex, and wheresaid composition comprises at least 7.0% articaine, and has a pH ofabout pH 6.0 to pH 7.0.
 29. The method of claim 28, wherein saidborate/mannitol complex is obtained from a borate/mannitol ratio ofabout 1:3 to about 1:7 by weight.
 30. The composition of claim 15,wherein said composition has an osmolality of 500 to 700 mOsms/kg. 31.The composition of claim 30, wherein said composition has a pH of 4.5 to7.0.
 32. The composition of claim 31, wherein said composition contains7.5% to 8.8% w/v articaine.
 33. The composition of claim 30, whereinsaid composition has an osmolality of 580 to 630 mOsms/kg.